The question of recalling any number of members of the commission may be submitted at the same election, but as to each member whose removal is sought a separate petition shall be filed and provision shall be made for an entirely separate ballot. Candidates to succeed any member of the commission whose removal is sought shall be placed in nomination by petition, signed, filed and verified as provided for nominating petitions for a regular municipal election; except that each petition paper shall specify that the candidate named therein is a candidate to succeed a particular member of the commission whose removal is sought. The petition shall be filed not less than thirty days before the date of the recall election.